Hiding behind the town’s high mud-brick walls are hundreds of large traditional houses built by wealthy merchants, monuments to the importance of Kashan as a Qajar-era commercial hub. Built during the 19th century, most have long since been divided into smaller homes and many are literally turning to dust. A few, however, have been restored and are open to the public as museums or as Kashan's most desirable places to stay.

　　While each house has its own distinct features (the tallest wind catcher, the best plaster work, the most courtyards), they all share a common principle of design. The house is arranged around a series of interlinked courtyards, each with a separate function: the andaruni served as the internal area where family members lived; the biruni acted as an external area used for entertaining and housing guests and conducting business; and the khadameh (servants’ quarters). Designed to be plain and modest from the outside, with no house exceeding the height of any other, the doorways show little hint of the wonders within. Even the receiving area is concealed from the courtyard by angled corridors, perhaps to ensure privacy, or perhaps to increase the impact of stepping into the first courtyard. High thresholds and low door frames into each room were built partly to keep scorpions at bay, and partly to enforce a bow on entry.

　　Each courtyard is arranged around a central garden with a water feature (usually a rectangular pool with fountains) and includes a warm south-facing seating area that catches the winter sun, and an opposing north-facing area for warmer months. Lofty badgirs channel the prevailing winds into a basement used for escaping the summer heat. The houses are full of aesthetic wonders, including elaborate stucco work, stalactite ceilings, painted murals, and gorgeous coloured glass and wood panelling. They make a refreshing place simply to sit and enjoy the garden or watch as others pause to catch their reflection in the glass work or stoop to scoop up coloured sunbeams.